Camera dolly track assembly

ABSTRACT

A support for a camera dolly comprising spaced-apart first and second rails comprised of longitudinal rail members. The first rail has a first seam between its rail members, and the second rail has a second seam between its rail members. The first seam in the first rail is directly opposed from a corresponding second seam in the second rail. The first and second seams have first and second leading edges formed at crowns on the first and second rails, and the leading edge of the first seam is offset longitudinally with respect to the leading edge of the corresponding second seam.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/808,408, filed Apr. 4, 2013, which is hereby incorporated byreference.

FIELD OF THE INVENTION

The present invention relates generally to camera equipment, and moreparticularly to tracks for supporting and guiding camera equipment.

BACKGROUND OF THE INVENTION

Video cameras, such as those used in professional media productionsettings, are highly sensitive pieces of equipment that must frequentlybe moved during filming to capture specific cinematographic shots. Videocameras respond to the slightest movement, and often do so in uncertainor undesirable ways. For that reason, the motion picture industry hasdeveloped many techniques and tools for stabilizing a camera duringmotion to reduce the undesirable effects of ancillary movements.

The motion picture industry has produced numerous types of tracks formoving a video camera smoothly from a first point to a second point.These tracks typically consist of two opposed, elongate rails secured toopposed bases. A chassis or dolly rides the rails between the bases onwheels or feet that glide over the rails of the track, and the videocamera is mounted to the dolly.

For short runs, a track constructed of a single span of rails is ideal.However, cameras must often be moved longer distances. For instance, ashot that follows a surfer running down a beach and into the water mayrequire that the camera move with the surfer fifty feet or more. A trackis typically assembled along that distance to produce a stable, smooth,moving shot down the beach. In situations where the camera moves morethan a short distance, a track assembly is constructed from many railmembers coupled together in series. However, the junction between therail members often is uneven, and as the camera dolly rolls over thejunction, the dolly may be jarred or may vibrate, causing the camera toshake slightly. That shake will be translated permanently to the film.If the vibration in the filmed scene can be fixed, it will have to bereduced or eliminated in post production, which can be time-consumingand expensive. An improved track for a camera dolly is needed.

SUMMARY OF THE INVENTION

According to the principle of the invention, a camera dolly trackassembly includes spaced-apart, opposed first and second rails eachhaving a rolling surface for supporting a camera dolly. Each rollingsurface includes two divergent faces depending from a common crownextending a complete length of each rail. The rolling surfaces aresevered by seams between the rail members. Each seam defines a planealigned obliquely with respect to the rolling surface, such that whenthe camera dolly rolls over the seam, wheels of the camera dollyencounter the seam at different moments, thereby reducing the impact orjarring to the camera dolly.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring to the drawings:

FIG. 1 is a top perspective view of a camera dolly track assemblyconstructed and arranged according to the invention, including two railsconstructed of rail members extending between opposed base assemblies,and a camera dolly supported on the rails;

FIG. 2 is an enlarged side perspective view of seams formed between therail members of the rails of FIG. 1, with wheels of the camera dollyjust above;

FIG. 3 is a side perspective view of two of the rail members of therails of FIG. 1 fixed with a coupler and unattached to neighboring railmembers;

FIG. 4 is similar to FIG. 3, but illustrates neighboring rail membersfixed on the coupler and juxtaposed with the two rail members, formingseams;

FIGS. 5, 6, and 7 are top perspective, bottom perspective, and frontelevation views, respectively, of the coupler of FIG. 3;

FIG. 8 is a side perspective view of the rails of FIG. 1 secured on thebase assembly, showing couplers within the rails partially in brokenline;

FIGS. 9 and 10 are top perspective and bottom perspective views,respectively, of the coupler of FIG. 8; and

FIG. 11 is an enlarged side perspective view of the camera dolly ridingon the rails of FIG. 1.

DETAILED DESCRIPTION

Reference now is made to the drawings, in which the same referencecharacters are used throughout the different figures to designate thesame elements. FIG. 1 illustrates a camera dolly track assembly 20constructed and arranged according to the principle of the invention,and carrying a dolly 21 for supporting a camera. The track assembly 20includes two opposed, spaced-apart rails 22 and 23 extending between twoopposed base assemblies 24 and 25. The rails 22 and 23 provide a smoothrolling surface for carrying the dolly 21 to ensure that a camerasupported on the dolly 21 moves without interruption or disturbance,thus providing a smooth filming environment.

The rails 22 and 23 are identical in every respect, other than locationand orientation, and as such, only the rail 22 will be described, withthe understanding that the discussion of the rail 22 applies equally tothe rail 23, but for location and orientation characteristics which areseparately described. Further, the various elements and structuralfeatures of the rail 23 will carry the same reference characters asthose of the rail 22, but will be designated with a prime symbol (“′”)so as to identify and distinguish the elements and features of the rail23 from those of the rail 22. In some cases, reference to the elementsand features of the rail 23 may be made where clarity of the FIG. makessuch reference easier. The rail 22 includes several rail members 30coupled together in series, and only one rail member 30 will be referredto for simplicity.

The rail member 30 is constructed of a material or combination ofmaterials have rigid, strong, rugged, and durable materialcharacteristics, which can be ground or applied with a smooth finish,such as metal. The rail member 30 has opposed ends 31 and 32 and threeoutward faces 33, 34, and 35 extending between the ends 31 and 32. Theoutward faces 33 and 34 are upward faces which carry the dolly 21 rolls,and the outward face 35 is a downward face, and is formed with fasteningstructures for coupling to the other rail members 30 and to the baseassemblies 24 and 25. As seen in FIG. 2, the rail member 30 is prismaticand has a generally triangular cross-section. The outward face 35 isformed on a bottom 40 of the rail member 30, and the outward faces 33and 34 extending up from the bottom 40 are formed on sides 41 and 42,respectively, of the rail member 30. The sides 41 and 42 of the railmember 30 meet at a common, elongate crown 43 at the top of the railmember 30 which extends completely along the rail member 30 between theends 31 and 32.

Still referring to FIG. 2, an oblique seam 47 is formed between the railmembers 30. The seam 47 is formed between the end 31 of one rail member30 and the opposing end 32 of an opposing rail member 30. The seam 47extends from a trailing edge 48, located at the bottom 40 of the railmember 30, upward at an angle to a leading edge 49 located at the crown43 of the rail member 30.

FIG. 3 further illustrates two ends 31 and 32 of rail members 30 in boththe rails 22 and 23. FIG. 3 is a side perspective view directed onto andslightly above both the rails 22 and 23. At the end 31 of the railmember 30 in the rail 22, the bottom 40 of the rail member 30 projectsfurther away from the rail member 30 than the crown 43, defining thelocation of the trailing edge 48 (though the trailing and leading edges48 and 49 are part of the seam 47 formed by juxtaposed rail members 30,it should be understood that the location of the trailing edge 48 isstill clearly shown in FIG. 3 even with the presence of only rail member30, and that the actual seam 47 is shown in FIG. 3). The trailing edge48 lies in a plane A extending through both of the rails 22 and 23vertically with respect to those rails 22 and 23. The seam 47 extendsfrom the trailing edge 48 to the leading edge 49 at the crown 43 of therail member 30. The leading edge 49 lies in a plane B extending throughboth of the rails 22 and 23 vertically with respect to those rails 22and 23. The planes A and B, both shown in FIG. 3 in broken line asextending into and out of the page, are parallel to each other. Theplanes A and B bound and define a longitudinal seam zone 39 for both ofthe rails 23 and 22, in which the seam 47 is entirely disposed andsnugly confined.

The end 31 is angled with respect to the planes A and B, which eachextend through the rail member 30 transverse to the rail member 30. Theend 31 is aligned at an angle θ to the planes A and B, as seen in FIG.3. Angle θ is approximately fifteen degrees, and is preferably betweenten and twenty degrees with respect to the planes A and B, resulting inthe end 31 being oblique to the rail member 30 at an angle of preferablybetween approximately seventy and eighty degrees. The end 32′ of therail member 30′ of the rail 23 in FIG. 3 likewise forms an angle θ′ withthe planes A and B.

FIG. 3 shows two ends 31 and 32′ of the rails 22 and 23, respectivelywith uncoupled rail members 30 and 30′. FIG. 4, on the other hand, showsthe rails 22 and 23 with coupled rail members 30 and 30′, forming theseams 47 and 47′ between the rail members 30 and 30, between the railmembers 30′ and 30′, respectively, as they would typically arranged toform the track assembly 20 of FIG. 1. Again referring primarily to therail 22, the rail members 30 are coupled end 31 to end 32 in series toform the rail 22, as shown in FIG. 4. Rails 22 and 23 of varying lengthcan be built by coupling rail members 30 in series together, and shorteror longer rails 22 and 23 can be built as the situation demands. Therail members 30 are coupled with couplers 50 which are inserted into theends 31 and 32 of the rail members 30 and hold rail members 30 securelyin alignment with respect to each other.

The seam 47 is formed between the ends 31 and 32 and is disposed acrossthe rail 22 through the longitudinal seam zone 39 in a first directionin a plane C defined by the seam 47. The plane C is shown in broken linein FIGS. 3 and 4. The seam 47′ is formed between the ends 31′ and 32′and is disposed across the rail 22 through the longitudinal seam zone 39in a second direction in a plane C′ defined by the seam 47′. The planeC′ is also shown in broken line in FIGS. 3 and 4. The seams 47 and 47′are directly opposed from each other on the rails 22 and 23, though theseams 47 and 47's are oriented in different first and second directions.The planes C and C′ are transverse, or oblique, with respect to eachother and intersect each other at an angle two times angle θ, since theplane C is aligned at angle θ with respect to the plane A and the planeC′ is aligned at equal and opposite angle θ′ with respect to the planeB, as shown in FIGS. 3 and 4. Thus, the trailing edges 48 and 48′ areoffset longitudinally with respect to each other, and the leading edges49 and 49′ are also offset longitudinally with respect to each other.

Referring back to FIG. 2, the rail member 30 is formed with a hollowinterior 51 that extends completely through the rail member 30 betweenand through the ends 31 and 32. The interior 51 is generally triangularand is sized to receive the coupler 50, shown in FIGS. 5, 6, and 7. Theinterior 51 is bound by two upper inner surfaces and a lower innersurface. Two threaded holes 52 extend through the bottom 40 of the railmember 30 from the outward face 35 through the lower inner surfaceproximate to the end 31, and two threaded holes 53 extend through thebottom 40 from the outward face 35 through the lower inner surfaceproximate to the end 32.

Referring now to FIGS. 5, 6, and 7, the coupler 50 is shown in topperspective, bottom perspective, and front elevation views,respectively. The coupler 50 secures the end 31 of one rail member 30 tothe end 32 of another, neighboring, rail member 30 securely andprecisely. The coupler 50 is elongate and generally triangularprismatic, having two upper faces 54 and 55 which meet and join along adepressed top 60, and a lower face 61 formed with an inner rib 62extending along the coupler 50. The top 60 and the inner rib 62 arereinforced and thicker than the remainder of the coupler 50, providingaxial strength and rigidity to the coupler 50. The coupler 50 hasopposed ends 63 and 64, and two sets of threaded holes 65 and 66 areformed completely through both the lower face 61 and the inner rib 62proximate to the ends 63 and 64, respectively. The coupler 50 isconstructed of a material or combination of materials having rigid,durable material characteristics, and which can be smoothed to a finefinish, such as metal.

Referring to both FIGS. 3 and 7, to couple the rail members 30 together,the coupler 50 is first inserted into one end 31 of the rail 22, and theholes 65 in the coupler 50 are aligned with the holes 52 in the railmember 30. The upper faces 54 and 55 of the coupler 50 are received injuxtaposition against the upper inner surface of the interior 51 of therail member 30, and the lower face 61 of the coupler 50 is received injuxtaposition against the lower inner surface of the interior 51 of therail member 30. In this way, the coupler 50 has a loose press fit insidethe rail member 30. Threaded bolts 70 are then rotatably applied andthreadably engaged to the aligned holes 65 and 52, and a shank of eachbolt 70 extends into, through, and past the inner rib 62 of the coupler50 until the shank contacts the top 60 of the coupler 50. As seen inFIG. 7, the bolt 70 carries a washer 71 encircling the shank proximateto a head of the bolt 70, and, as seen in FIG. 3, the washer 71 contactsthe bottom 40 of the rail member 30. Continued application of the bolt70 through the holes 65 and 52 causes the washer 71 to tighten againstthe bottom 40 and urges the shank into the top 60 of the coupler 50,causing the coupler 50 to expand against the rail member 30. The railmember 30 is constructed of a rigid, strong, rugged, and durablematerial or materials, and as such, resists expansion. Expansion of thecoupler 50 against the rail member 30 forms a tight press fit betweenthe coupler 50 and the rail member 30, so that the rail member 30 issecured on the coupler 50.

Referring now to FIG. 4, an end 32 of another rail member 30 is thensimilarly secured on the coupler 50, with end 31 received in flushcontact in juxtaposition with the end 32, forming the seam 47. At theseam 47 between the ends 31 and 32, the crowns 43 of each rail member 30are aligned longitudinally, the bottoms 44 are aligned and parallel, andthe sides 41 and 42 are aligned and parallel. The coupler 50 tightlybinds the ends 31 and 32 together and tightly binds the rail members 30together. In this manner, two or more rail members 30 are joined to formthe rail 22.

The rail 22 extends between opposed base assemblies 24 and 25, as shownin FIG. 1. The base assemblies 24 and 25 are directed toward each other,and capture and securely hold the rails 22 and 23 therebetween. The baseassemblies 24 and 25 are identical in every respect other than locationand orientation, and as such, only the base assembly 24 will bedescribed, with the understanding that the discussion of the baseassembly 24 applies equally to the base assembly 25, but for locationand orientation characteristics which are separately described. Further,the various elements and structural features of the base assembly 25will carry the same reference characters as those of the base assembly24, but will be marked with a prime (“′”) so as to identify anddistinguish the elements and features of the base assembly 25 from thebase assembly 24. Turning now to FIGS. 8-10, the base assembly 24includes two opposed mounts 80, two opposed sleeves 81 for receiving themounts 80, a brace 82 extending between the sleeves 81, and a post 83supporting the brace 82. The post 83 is a hollow cylinder extendingupward from an open end and terminating at the brace 82. The post 83 issuitable for mounting on a heavy or stable base disposed on the ground,a fixed pole or post, or whatever surface is selected by the grip forarrangement of the scene to be filmed. The brace 82 is a rigid, stronghorizontal member having opposed ends 84 and 85. The sleeves 81 aredisposed at the ends 84 and 85, and are each formed integrally or weldedto the brace 82 at the ends 84 and 85. The sleeves 81 are each short,horizontal tubes having an inner, cylindrical, female engagement area 86for receiving and holding the mounts 80. Two threaded holes extendthrough each of the sleeves 81 for accepting a threaded shank of a boltor set screw 87.

The mounts 80 have a structure similar to the couplers 50. As shown inFIGS. 9 and 10, the mount 80 has a cylindrical fixture defining a maleengagement fixture 88 for coupling with the female engagement area 86 inthe base assembly 24. The mount 80 further includes a bracket 90,constructed similarly to the coupler 50, mounted to a bar 91 andextending axially outwardly from the from the male engagement fixture88. The bar 91 is permanently mounted within the male engagement fixture88, such as by welding, and extends out of the male engagement fixture88. The bracket 90, like the coupler 50, has two upper faces 94 and 95,a top 100, a lower face 101, and an inner rib 102. Two threaded holes 92are formed through the lower face 101 for receiving two threaded bolts93.

To mount the rail 22 to the base assembly 24 as in FIG. 8, the mounts 80are first secured within the sleeves 81. The male engagement fixture 88of each mount 80 is passed into the female receiving area 86 of thesleeve 81, and the set screws 87 are tightened onto the male engagementfixture 88, securely and rigidly fixing the mounts 80 within the sleeves81. The bracket 90 is then available for receiving the rail 22.

Still referring to FIG. 8, the end 31 of the rail member 30 is alignedwith and moved over the bracket 90, the bracket 90 is inserted into theend 31 of the rail member 30, and the holes 92 in the bracket 90 arealigned with the holes 52 in the rail member 30. The upper faces 94 and95 of the bracket 90 are received in juxtaposition against the upperinner surface of the interior 51 of the rail member 30, and the lowerface 101 of the bracket 90 is received in juxtaposition against thelower inner surface of the interior 51 of the rail member 30. In thisway, the bracket 90 has a loose press fit inside the rail member 30.Threaded bolts 93 are then rotatably applied and threadably engaged tothe aligned holes 65 and 92, and a shank of each bolt 93 extends intoand past the inner rib 102 of the bracket 90 until the shank contactsthe bar 91. The bolt 93 carries a washer encircling the shank proximateto a head of the bolt, and the washer contacts the bottom 40 of the railmember 30. Continued application of the bolt 93 through the holes 65 and92 causes the washer to tighten against the bottom 40, and urges theshank of the bolt 93 upwards into the bar 91 against the bracket 90,causing the bracket 90 to expand against the rail member 30. Expansionof the bracket 90 against the rail member 30 forms a tight press fitbetween the bracket 90 and the rail member 30, so that the rail member30 is secured on the bracket 90 and on the base assembly 24. Both rails22 and 23 are secured to the base assemblies 24 and 25 in this manner,forming the track assembly 20.

With the track assembly 20 formed, the track assembly 20 can receive thedolly 21 for rolling movement across the rails 22 and 23. As shown inFIG. 11, the dolly 21 is positioned on top of the rails 22 and 23. Thedolly 21 has wheels 103 with rotational axes D oriented in the sameplane as the planes A and B (as shown in FIGS. 3 and 4). However, theaxes D are offset or angled with respect to the orientation of the seams47 between the rail members 30, as seen in FIG. 11. As the wheels 103roll along the track 22, each wheel 103 has a contact area 104 (shown inbroken line in FIG. 11) extending across the width of the wheel 103which is parallel to the axis B and to the planes A and B. This contactarea 104 is thin, but does extend across the full width of the wheel103. The contact area 104 is the site of contact between the dolly 21and the track 20, and any irregularities in the rails 22 and 23 would becommunicated to the dolly as bumps and vibrations when the contact area104 moves over those irregularities.

As seen in FIG. 11, the rail 22 has a rolling surface 105. The rollingsurface 105 includes the outward faces 33 and 34 which are divergent,elongate faces depending from the crown 43. The rolling surface 105 isthus a folded surface having the two outward faces 33 and 34 directedaway from each other on a triangular cross-sectioned rail member 30. Therolling surface 105 is severed obliquely by the seam 47.

As the dolly 21 rolls forward on the track 20 in a direction generallyindicated by the line E in FIG. 11, the wheels 103 of the dolly 21 rollover the rolling surface 105 and cross the seam 47 at different momentsbecause each wheel 103 is spaced apart. Furthermore, different portionsof each wheel 103 cross the seam 47 at different moments because thecontact area 104 for each wheel is transverse with respect to the seam47. The contact area 47 of the leading wheel 103 moves over a portion ofthe seam 47 that is proximate to the crown 43 first, because the seam 43is angled. As the contact area 104 advances further along the rail 22,the contact area 104 moves toward a portion of the seam 47 that isproximate to the bottom 40 of the rail member 30. Thus, as the wheel 103rolls down the rail 22, the contact area 104 moves over the seam 47gradually from one end of the seam 47 to the other end of the seam 47.The seam 47 is thus introduced gradually to the contact area 104,eliminating any bump or vibration between the wheel and the seam 47. Theother wheels 103 progress over the seam 47 in the rail 22 in a similarmanner.

Likewise, the wheels 103′ roll over the seam 47′ in a similar manner,but the seam 47′ is directed opposite to the seam 47. In this way, asthe wheel 103 rolls over the seam 47 in the rail 22 proximate the crown43 first, the wheel 103′ rolls over the seam 47′ in the rail 23proximate the bottom 40 first, so that the wheels 103 and 103′ encounterdifferent portions of the respective seams 47 and 47′ at differentmoments, further reducing any potential jarring or vibration imparted tothe dolly 21.

The present invention is described above with reference to a preferredembodiment. However, those skilled in the art will recognize thatchanges and modifications may be made in the described embodimentwithout departing from the nature and scope of the present invention. Tothe extent that such modifications and variations do not depart from thespirit of the invention, they are intended to be included within thescope thereof.

Having fully and clearly described the invention so as to enable onehaving skill in the art to understand and practice the same, theinvention claimed is:

The invention claimed is:
 1. A support for a camera dolly, the supportcomprising: spaced-apart, opposed first and second rails each having arolling surface for supporting the camera dolly and extending along therespective first and second rails; each rolling surface including twodivergent elongate faces depending from a common crown of the respectivefirst and second rails; and each rolling surface is severed by a seamextending transversely across each of the divergent faces of therespective rolling surface and defining a plane aligned obliquely withrespect to the respective rolling surface.
 2. The support of claim 1,further comprising: the plane defined by the seam severing the rollingsurface of the first rail is a first plane; the plane defined by theseam severing the rolling surface of the second rail is a second plane;and the first and second planes are transverse with respect to eachother.
 3. The support of claim 1, wherein the seams in the first andsecond rails are directly opposed from each other.
 4. The support ofclaim 3, wherein the seam in the first rail at the crown of the firstrail is offset from the seam in the second rail at the crown of thesecond rail.
 5. The support of claim 1, wherein each of the planes arealigned at between approximately seventy degrees and approximatelyeighty degrees with respect to the first and second rails.
 6. Thesupport of claim 1, wherein the first and second rails have triangularcross-sections.
 7. The support of claim 1, wherein: a coupler insideeach of the first and second rails joins the first and second rails ateach seam, respectively; each coupler has two opposed upper faces and abottom; and bolts extending through each of the rails proximate to theseam move between loosened conditions, defining a loose fit engagementbetween the coupler and the rail, and tightened conditions, defining asecured engagement in which the faces of the coupler are expandedagainst the rail.
 8. The support of claim 1, wherein the first andsecond rails are identical and aligned opposite each other.
 9. A supportfor a camera dolly, the support comprising: a first rail including firstrail members joined in longitudinal extension at a first seam; a secondrail including second rail members joined in longitudinal extension at asecond seam, the second rail spaced apart from and opposite to the firstrail; the first and second seams are disposed transversely across thefirst and second rails in a longitudinal seam zone common to both thefirst and second rails and defined between first and second planesperpendicular to the first and second rails; the first seam extendsthrough the longitudinal seam zone in a first direction; and the secondseam extends through the longitudinal seam zone in a second directiontransverse to the first direction of the first seam.
 10. The support ofclaim 9, wherein: the first and second rails each have two sidesextending between a crown and a bottom opposite the two sides; the firstseam extends through the longitudinal seam zone from the bottom of thefirst rail at the first end to the crown of the first rail at the secondend; and the second seam extends through the longitudinal seam zone fromthe bottom of the second rail at the second end to the crown of thesecond rail at the first end.
 11. The support of claim 9, furthercomprising: the first seam of the first rail is aligned obliquely withrespect to the first rail members; and the second seam of the secondrail is aligned obliquely with respect to the second rail members. 12.The support of claim 9, wherein the first and second rail members havetriangular cross-sections.
 13. The support of claim 9, wherein the firstand second seams are aligned at between approximately seventy degreesand approximately eighty degrees with respect to the first and secondrails, respectively.
 14. The support of claim 9, wherein the first andsecond rail members are identical and aligned opposite each other.
 15. Asupport for a camera dolly, the support comprising: spaced-apart firstand second rails comprised of longitudinal rail members; the first railhas a first seam between the rail members of the first rail; the firstseam in the first rail is directly opposed from a second seam in thebetween the rail members of the second rail, the first seam therebycorresponding longitudinally to the second seam; the first and secondseams have first and second leading edges formed at crowns of the firstand second rails, respectively; and the leading edge of the first seamis offset longitudinally with respect to the leading edge of the secondseam.
 16. The support of claim 15, further comprising: the first seam ofthe first rail is aligned obliquely with respect to the rail members ofthe first rail; and the second seam of the second rail is alignedobliquely with respect to the rail members of the second rail.
 17. Thesupport of claim 16, wherein the first seam in the first rail is alignedtransverse with respect to the second seam in the second rail.
 18. Thesupport of claim 15, wherein the first and second rails have triangularcross-sections.
 19. The support of claim 15, wherein the first andsecond seams are aligned at between approximately seventy degrees andapproximately eighty degrees with respect to the first and second rails,respectively.
 20. The support of claim 15, wherein the rail members ofthe first and second rails are identical and aligned opposite eachother.